As a common production method of castings, casting has been developed and innovated for many years. At present,, investment casting, pressure casting and EPC casting are commonly used in practical production.
Casting is an early metal processing technology mastered by human beings. It has a history of about 6000 years, among which it occupies a large proportion in the machinery industry. Casting can produce various shapes of rough. With a long history, this production mode has accumulated enough practitioners and technical experience, so the production cost is relatively low. At the same time, it has a wide adaptability and good comprehensive mechanical properties. For a long time, it has been widely used in various industrial departments such as machinery, chemical industry, aviation, aerospace, etc., with complex structure and strict technical requirements Casting technology is a stable and economical production method for a long time. There are many casting methods, sand casting is one of them. The production mode of sand casting: the metal liquid fills the gap between the sand molds to form the casting. After the metal liquid solidifies, the sand is shaken down by the desander, and then cleaned to obtain the advantages of rough sand casting, mainly including the following aspects:
(1) The production mode is flexible and efficient. A variety of production methods, can be manual, can also be automated mechanical production, can be a single, can also be a large number.
(2) It has a wide range of applications. The products that can be produced by sand casting are almost unlimited by the size of castings. They can be used from several grams to thousands of tons. The wall thickness can also be from several millimeters to tens of meters. If the core is made by hand with multiple live blocks, the shape of castings can be very complex.
(3) Low cost. Due to the low price of the materials used in sand casting, the simple manufacture of the mold, the technology accumulation over the years and the mature technology in the industry, and many practitioners, the cost of casting is more advantageous than other metal forming methods.
In the, 80% of the products on W are made by sand casting, and the clay King sand mold accounts for the vast majority of them. In the early days of the founding of the people’s Republic of China, the proportion is still higher. In the mid-1950s, the main raw materials for natural sand sticking, water washing and quartz sand transport molding were used. Since 1960s, activated bentonite has been used in some foundries in China. However, due to the lack of mineral deposits, it is difficult to mine the natural Na bentonite, so up to now, the artificial activated bentonite has occupied the majority
In the early 1980s, Shenyang Foundry Research Institute and Tsinghua University studied the scrubbing process of the original sand. After that, many molding sand factories began to use the scrubbing process in the production of the original sand. After that, natural silica sand flotation technology and shaping sand processing technology appeared, and the development of some processing technology improved the quality of quartz. From the eighth five year plan to the twelfth five year plan, China’s foundry industry has maintained a strong growth trend under the huge market demand, during which China has successively developed castings that can be used for general castings Equipment, to a certain extent, alleviated the urgent demand of domestic industry for foreign equipment at that time.
Generally speaking, in our country, the design and manufacturing department of casting mold is subordinate to the foundry (company), which is equivalent to an auxiliary department. Casting mold is only a tool in the production process. The result is that the employees should know a little about all aspects of knowledge, but they are not precise, the labor cost is too high, the management link is not smooth, the employees lack of crisis sense, the mold manufacturing cycle and The quality cost is irrelevant, and the improvement of technical level depends entirely on the input of equipment, while the input of mold is restricted by the foundry, which is difficult to be included in the plan of the foundry. Finally, the benefit of the foundry is not good, the quality of mold is reduced, and the quality of casting is affected, resulting in a vicious cycle. In recent years, the rise of some private professional mold manufacturers has proved that the only way out for the development of casting mold is to get rid of the shackles of planned economy, act according to the market rules, take casting mold as the product, and strengthen the awareness of mold quality, service and supply. Now some large state-owned enterprises have begun or basically completed the restructuring. Some enterprises have concentrated their efforts to merge the casting mold and other molds, and set up independent mold companies to operate; some simply simplify the mold manufacturing that they can’t do well, and completely entrust it to professional mold manufacturers. Either way, it indicates the development trend of the casting die industry in today’s society, that is to say, it is in the transition to a specialized, automated and efficient way.